Electrochemical cells that generates hydrogen are known in diverse structural forms. In particular, such cells are frequently constructed as button cells. An exemplary construction of such cells is described in DE 3532335 A1.
Generation of hydrogen is based on an electrochemical reaction in cells as described in DE 3532335 A1. As a current flows through a cell, which comprises a metal such as zinc as the anode, i.e. an electrochemically oxidizable substance, and a catalyst electrode capable of decomposing water as the cathode, hydrogen is formed. Such cell types contain an aqueous alkaline electrolyte as the electrolyte.
Known hydrogen evolution cells comprise a housing having at least one aperture as a gas outlet opening, through which generated hydrogen can escape from the interior of the housing. The aperture is required for operation of the cells. During longer storage, materials such as carbon dioxide or atmospheric oxygen can penetrate into the housing interior and result in undesired chemical reactions therein. For this reason, the at least one aperture is generally covered using a detachable sticker in the form of a label having a small grip tab. Cells protected in this manner are shown, for example, in FIG. 1 of EP 1325876 B1. Before startup of the cells, the detachable sticker is removed for many applications, however. This is because hydrogen generated in the cell has to be able to exit from the housing interior with as few problems as possible. This is not only expedient for proper operation of the cells, but can even be required for safety reasons. In the hydrogen evolution cells known from DE 3532335 A1, in the event of unintentional blockage of the gas outlet opening, pressures can form which are sufficiently high to cause the cells to burst.
There are numerous applications for hydrogen evolution cells as described in DE 3532335 A1. They are used very frequently in conjunction with the dispensing of free-flowing media. Thus, the generated hydrogen can drive, for example, the piston of a grease dispenser, as described in DE 3532335 A1. The use of hydrogen-generating cells to dispense disinfectants and fragrances from fragrance dispensers is known from EP 2674623 A1.
In hydrogen evolution cells such as the cells described in DE 3532335 A1 having a zinc anode, the hydrogen evolution generally runs spontaneously when the anode is electrically connected to the cathode. A load resistance connects between the anode and the cathode to set the hydrogen evolution rate. This load resistance is generally a part of a larger device such as, for example, the mentioned fragrance dispensers. The hydrogen evolution cell is used therein. An essentially constant hydrogen evolution then occurs in operation. A subsequent adaptation of the hydrogen evolution rate is only possible with great effort. A replacement or an adaptation of the load resistance is required for this purpose.
It could therefore be helpful to provide hydrogen that enables a hydrogen evolution rate to be adapted later in existing devices such as the mentioned fragrance dispensers, without a load resistance integrated into the devices having to be adapted or replaced for this purpose.